The disclosure relates to the food service industry. More particularly, the disclosure relates to changeover valves for switching between two pouches or bags of foodstuff.
In the food service environment, it has become common for foodstuffs such as condiments, beverage syrups, dairy mixes, and the like to be dispensed from flexible containers such as plastic pouches or bags. Exemplary dispensing apparatus include condiment bar consoles, beverage machines, frozen dessert machines, and the like. The foodstuff may be drawn out of the pouch or bag (hereafter simply pouch) via a manual or automated pump.
To extend operation and provide foodstuff delivery continuity, it is known for such dispensing systems to include provisions for connecting two pouches of any given foodstuff and provide a changeover when one pouch empties. In one baseline system, one or more valves control communication between the pouches and the pump. In one example, flow paths from the respective pouches merge into a trunk passing through a pump to the dispenser outlet. A valve may be located along each of the two branches. An exemplary valve is a solenoid pinch valve operating on plastic tubing. In an initial situation, the first pouch is in the process of use and its associated valve is open; whereas the second pouch is full awaiting use and its associated valve is closed. During use, the pump eventually empties the first pouch whereupon further pumping is resisted and pressure in the trunk and first flowpath drops. This condition may be sensed via a pressure sensor, vacuum sensor, or vacuum switch along the trunk or first flowpath or may be sensed via pump current draw. Upon sensing this condition, a switchover is initiated wherein the dispenser's controller closes the first valve and opens the second valve. The opening of the second valve allows the pump to draw foodstuff from the second pouch. The closing of the first valve allows a user to replace the first pouch to facilitate a subsequent switchover from the second pouch to the replaced first pouch and so on.
U.S. Pat. No. 6,837,257, to Cedergren, Jan. 4, 2005, provides an automatic switchover via the use of a bi-stable magnetic shuttle valve. The shuttle has a first condition permitting communication along the first flowpath between the first pouch and the outlet while blocking communication along the second flowpath from the second pouch. Similarly, the shuttle has a second position in which the communication along the first flowpath from the first pouch is blocked and communication along the second flowpath from the second pouch is permitted. Two permanent magnets create a bi-stable relationship between the two positions. Pressure changes associated with the first pouch reaching essentially empty will overcome the magnetic bias and draw the shuttle toward the second position. The bi-stability will cause the shuttle to shift via a toggle action into the second position so that the foodstuff will begin to dispense from the second pouch and the first pouch may be replaced. Again, this process may alternate. This purely permanent magnet valve lacks controllability of electromagnetic valves.